This project is concerned with the evaluation of variety of new and existing diagnostic techniques which ave yet to be applied in dentistry. It is largely a continuation of work done in previous years which dealt with the development of quantitative methods for measuring factors believed to be associated with the development of quantitative methods for measuring factors believed to be associated with relatively long-term changes of diagnostic interest in dental tissues. Modalities studied include quantitative radiology, nuclear medicine (99mTc-MDP), fiber-optic systems making use of visible light (hemoglobin-specific spectrum analysis), and magnetic resonance (MR) imaging. New algorithms are being used to extend the application of digital subtraction radiography to include longitudinal assay of experimentally simulated, progressive, bone lesions in the phalanges and femur. Data show that gravimetrically determined focal lesions can be estimated with a precision of 0.5 mg. Radiometric assessment of scattered light continues to be used to evaluate tooth vitality. In vitro data obtained using a prototype, filtered, fiber-optic system design to detect the presence of oxygenated blood in the pulp chamber show that tiny changes in tooth color measured in this way can be used to predict degenerative changes seen invariably in recently extracted teeth after storage for a week or more in saline at 37 degree C. Measurements of differential uptake of 99mTc-MDP in beagle dogs following induction of tiny alveolar lesions indicated the need for redesign of the miniature nuclear probe to increase spatial specificity. MR imaging was investigated to determine whether surgically induced stenosis of the salivary gland ducts can be detected reliably. The results indicate that T2-weighted images show significant differences between occuled and nonocculed ducts with excellent representation of the anatomy.